Demag circuit not working on NAC MS9-29A

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fraggle200
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Demag circuit not working on NAC MS9-29A

Post by fraggle200 » May 17th, 2019, 11:01 am

I got a NAC a few weeks back and after cleaning it all out the next thing to address is the demag/degauss circuit. I've mostly cleared the issue on the monitor with a degaussing wand but I'd rather sort the circuit than rely on that permanently.

I've been all over here trying to find a definitive guide on where to start to get the demag circuit up and running on my MS9-29A and short of wiring in a new switch.... somewhere, I'm drawing a blank or just getting more confused.

If I was to wire in a switch should I do it at the PSU end of the wiring and hope everything after that is ok or should it be put into the wiring just coming from the amp up connector on the chassis? I've a 400-5198-01 PSU in the NAC so ideally I'd like to keep it as original as possible and use that for the Demag. Has anyone seen the switch in the PSU fail? If so, can it be fixed? All solder joints on the chassis seems good but could there be anything else on the chassis I should consider or could cause this issue?

I'm really trying to figure out the most efficient way of problem solving this as, Im sure everyone here is the same in that, I'd rather not have to spend hours on something if there's a reasonably simple way to determine where the fault is.

Thanks

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grantspain
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Re: Demag circuit not working on NAC MS9-29A

Post by grantspain » May 17th, 2019, 11:14 am

demag fault can only be wiring or ptc, i doubt its the ptc so wiring is most likely
you will need to check the connector on the chassis itself and continuity test the wires from that connector to your switch

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Re: Demag circuit not working on NAC MS9-29A

Post by fraggle200 » May 17th, 2019, 12:16 pm

Thanks

Thats given me a little more confidence in being able to narrow down the issue knowing it's most likely wiring.

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nem
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Re: Demag circuit not working on NAC MS9-29A

Post by nem » May 17th, 2019, 4:14 pm

The demag switch is just a regular contact switch. You could just as well bridge the contact points with a screwdriver.

The 3-pin connector on the left in the D circle:

http://i38.tinypic.com/2yx52f5.jpg

Can't remember offhand which two pins you needed to bridge. I want to say middle and bottom.

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Re: Demag circuit not working on NAC MS9-29A

Post by fraggle200 » May 17th, 2019, 11:42 pm

Ah, i thought it was the 2 pin on the right.

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nem
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Re: Demag circuit not working on NAC MS9-29A

Post by nem » May 18th, 2019, 10:15 am

The 2-pin is for the coil around the tube. If that is unplugged that's your reason for it not working.

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Re: Demag circuit not working on NAC MS9-29A

Post by fraggle200 » May 20th, 2019, 4:04 pm

Well I put a momentary switch on the wiring and still nothing. Continuity all checks out on connectors and wiring.

Any other ideas?

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Re: Demag circuit not working on NAC MS9-29A

Post by PrincessPrinPrin » May 20th, 2019, 6:45 pm

I see there are two variants:
MS9deg.jpg
I only had the top one (with the black jumper wire) and know that the switch (red wires) is wired correctly there. The other type is wired differently so perhaps the PCB is also different.

What type do you have and how is it wired?
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Re: Demag circuit not working on NAC MS9-29A

Post by fraggle200 » May 22nd, 2019, 7:51 pm

I'm not at home just now to check but hazarding a guess I'd say the top one.

Not sure if this http://www.neo-arcadia.com/forum/viewtopic.php?t=47788 is a similar issue to what I'm having, if all the wiring checks out.

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